Two-Dimensional Electron Gas In Cubic Alxga(1-X)N/Gan Heterostructures

We report on the optical and electrical properties of cubic AlxGa1-xN/GaN heterostructures. The optical properties were investigated by photoluminescence measurements. A luminescence band at 3.250 eV was observed with our cubic AlxGa(1-x)N/GaN heterostructures. The emission lies between the excitonic emission of c-GaN at 3.276 eV and the donor-acceptor transition at about 3.135 eV. With increasing excitation power we find a characteristic blue shift of 4.5 meV/decade. To confirm the existence of a two-dimensional electron gas the transition energy versus externally applied voltage has been investigated. A 1.3 meV/V shift was measured and quantitatively verified by a self consistent solution of the Schrodinger and Poisson equation. The electrical properties were determined by capacity-voltage (CV)-measurements. The measured carrier profile is in excellent agreement with theoretical simulations and showed a sheet carrier concentration up to n = 1.6 x 10(12) cm(-2) at the AlxGa1-xN/GaN interface. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.